Methods and apparatus for adjusting blood circulation

ABSTRACT

Embodiments of the invention include a method and a device for increasing blood flow and controlling the temperature of a mammal by applying a desired pressure to extremities of a mammal. The device generally includes a pliant body element that is adapted to receive a portion of an extremity of the mammal therein, and then apply a pressure to a portion of the extremity when a pressure is provided to a region in which the extremity is positioned within the pliant body element. By evacuating the region in which the extremity is enclosed, a contact surface area between the extremity of a mammal and the pliant body element is increased, due to the external atmospheric pressure acting on the pliant body element against the skin of the extremity of the mammal. The application of pressure assures that sufficient contact and thermal heat transfer (heating or cooling) is provided to the extremity of the mammal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 15/261,676, filed Sep. 9, 2016, which is a continuation of U.S.patent application Ser. No. 13/736,843, filed Jan. 8, 2013, which is nowpatented as U.S. Pat. No. 9,463,134, which is a divisional of U.S.patent application Ser. No. 11/870,780, filed Oct. 11, 2007, which isnow patented as U.S. Pat. No. 8,603,150, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/868,542, filed Dec. 4,2006, and the benefit of the U.S. Provisional Patent Application Ser.No. 60/896,460, filed Mar. 22, 2007. Each of the aforementioned patentsand patent applications are herein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the invention generally relate to methods and apparatusfor increasing blood flow and/or adjusting and maintaining the coretemperature of a human.

Description of the Related Art

Homoiothermic animals, such as humans, strive to maintain relativelyconstant internal temperatures despite temperature variations in ambientenvironments and fluctuations in internal heat released as cellularmetabolism byproducts. In humans, the thermal core generally includesthe vital organs of the body, such as the brain and the several organsmaintained within the abdomen and chest. Peripheral tissues, such as theskin, fat, and muscles, act as a buffer between the thermal core and theexternal environment of the animal by maintaining a temperature gradientthat ranges from near-core temperature within internal organs tonear-ambient temperature at the surface of the animal.

Mammalian temperature regulation requires adaptations mechanisms, suchas insulation, respiratory heat conservation, and passive heatdissipation, etc., to enable mammalian survival without excessiveresource expenditure to generate a stable internal thermal environment.Insulation, internal or external, impedes heat transfer from ambientcondition to the body core and also protects animals from the cold.Subcutaneous insulation, similarly, retards the transfer of heat fromthe skin surface into the body core. The insulative properties ofperipheral tissues are determined by blood flow through the tissues andin the absence of blood flow, heat transfer through the tissues isnegligible. For example, lack of blood flow and poor blood perfusionmakes adipose tissues good insulators. Any tissues that are poorlyperfused may become insulators. Tissue blood perfusion determines localheat transfer and enables delivery of heat to (or removal from) a bodyregion.

Respiratory heat conservation is an adaptive mechanism to prevent heatloss, heat exchange between the circulating blood and the air at the gasexchange surface of the lung alveoli in mammals. All of the circulatingblood passes through the gas exchange surfaces of the lungs.

Heat is dissipated to the environment from the thermal core to the bodysurface by delivering through blood flow within the confines of thecirculatory system. The distribution of the systemic blood is inaccordance with local tissue metabolic demand. All blood passes throughthe chambers of the heart and the lungs. Cardiac output in a restinghuman is about 5 L/min so that the total blood volume circulates at aturnover rate of one cycle per minute. Blood volume and cardiac outputin mammals are insufficient to uniformly perfuse all tissues in thebody. Specialized vascular structures promote heat exchange in the bloodflow.

Two types of vascular structures are found in mammals: nutrient vascularunits and heat exchange vascular units. Their functions are mutuallyexclusive: The nutrient vascular units contain thin-walled, smalldiameter blood vessels uniformly distributed throughout the skin, suchas arterioles, capillaries, and venules, and require slow blood flowthrough to provide nutrients to local tissues. The heat exchangevascular units contain thick-walled, large diameter venules, such asvenous plexuses and Arteriovenous Anastomoses (AVAs; vascularcommunications between small arteries and the venous plexuses), andrequire flowing of large blood volumes to promote heat dissipation. Inhumans, the venous plexuses and AVAs of the heat exchange vascular unitsin humans are found mainly in the non-insulated palms of the hands,soles of the feet, ears, and non hairy regions of the face.

The thermoregulatory system in homoiothermic animals can be compromised(e.g., by anesthesia, trauma, or other factors) and may lead to thevarious thermal maladies and diseases. Under general anesthesia, apatient may be induced to loss the ability to conserve bodily heat.Thermal maladies, such as hypothermia and hyperthermia, can occur whenthe thermoregulatory system is overwhelmed by severe environmentalconditions. Constriction of the AVAs thermally isolates the body corefrom the environment, while, dilation of the AVAs promotes a freeexchange of heat between the body core and the environment.

Blood flow through the heat exchange vascular structures can beextremely variable, for example, high volume of blood flow during heatstress or hyperthermia can be increase to as high as 60% of the totalcardiac output. Hypothermia, on the other hand, is the result ofprolonged exposure to a cold challenge where blood flow through thevenous plexuses and AVAs can be near zero of the total cardiac output.Vasoconstriction of the peripheral blood vessels may arise underhypothermia in order to prevent further heat loss by limiting blood flowto the extremities and reducing heat transfer away from the thermal coreof the body. However, vasoconstriction makes it much more difficult toreverse a hypothermic state since vasoconstriction impedes the transferof heat from the body surface to the thermal core and makes it difficultto simply apply heat to the surface of the body. This physiologicalimpediment to heat transfer is referred to as a vasoconstrictiveblockade to heat exchange. There is a need to regulate blood flow to thevenous plexuses and AVAs of the heat exchange vascular units andintervene thermal maladies.

Other thermal malady related diseases, such as venous thromboembolicdisease, continues to cause significant morbidity and mortality.Hospitalization due to venous thrombosis and pulmonary embolism (PE)ranges from 300,000 to 600,000 persons a year. Following various typesof surgical procedures, as well as trauma and neurological disorders,patients are prone to developing deep vein thrombosis (DVT) and PE,which usually originate from blood clots in the veins and some clotstraveling to the lung. Regardless of the original reasons forhospitalization, one in a hundred patients upon admission to hospitalsnationwide dies of PE. Patients suffering from hip, tibia and kneefractures undergoing orthopedic surgery, spinal cord injury, or strokeare especially at high risk. Thus, prevention of DVT and PE isclinically important.

It is believed that slowing of the blood flow or blood return systemfrom the legs may be a primary factor related to DVT with greatesteffect during the intraoperative phase. Also of concern is thepostoperative period. Even individuals immobilized during prolong travelon an airplane or automobile may be at risk. Generally, withoutmobility, return of the blood back to heart is slowed and the veins ofan individual rely only on vasomotor tone and/or limited contraction ofsoft muscles to pump blood back to the heart. One study shows thattravel trips as short as three to four hours can induce DVT and PE.

Current approaches to prophylaxis include anticoagulation therapy andmechanical compression to apply pressure on the muscles throughpneumatic compression devices. Anticoagulation therapy requires bloodthinning drugs to clear clots in the veins which must be taken severaldays in advance to be effective. In addition, these drugs carry the riskof bleeding complications. Pneumatic compression devices, whichmechanically compress and directly apply positive message-type pressuresto muscles in the calf and foot sequentially, are not comfortable, aredifficult to use even in a hospital, and are too cumbersome for mobilepatients or for use during prolonged travel. In addition, most of themare heavy weighted and there are no portable or user friendly devices.

U.S. Pat. No. 5,683,438, issued to Grahn and assigned to StanfordUniversity, discloses an apparatus and method for overcoming thevasoconstrictive blockade to heat exchange by mechanically distendingblood vessels in a body portion and providing heat transfer to the bodycore of a hypothermic mammal. The disclosed device comprises afluid-filled heating blanket that is lodged within a tubular, elongatedhard shelled sleeve placed over the body portion. Sub-atmosphericpressure is applied and maintained within the sleeve. However, mostdevices for regulating body temperature may not provide sufficient heator adequate surface area for heat transfer being optimized and evenlydistributed between the heating element and the body of the patient. Inaddition, the devices may not be able to adapt to the variability inpatient sizes or provide mobility of the body portion during prolongtreatment.

Therefore, there remains a need for an apparatus and method to increaseblood flow to the venous plexuses and AVAs of the heat exchange vascularunits, thereby reducing the vasoconstrictive blockade and promoting heatexchange for body temperature regulation and disease intervention.

SUMMARY OF THE INVENTION

Embodiments of the invention provide methods and apparatus forincreasing blood flow and/or controlling body temperature which can beused in regulating body temperature to prevent and/or intervene thermalmaladies, deep vein thrombosis, PE and other disease arising from acompromised thermal regulatory system inside a mammal. In oneembodiment, a flexible extremity device is provided for regulatingtemperature and/or providing a vacuum or a negative pressure on anextremity of a mammal, such as a hand, an arm, a leg, foot, or calf of aleg, in order to increase blood flow on the extremity. According to anembodiment of the invention, the flexible extremity device can be usedin combination with a mechanical compression device or the flexibleextremity device can itself be modified to include one or morepressure-applying gas plenums in order to apply pressurized compressionforces to an extremity of a mammal, in addition to regulating thetemperature and/or applying vacuum to the extremity.

Embodiments of the invention provide a device for increasing blood flowand controlling body temperature, comprising a body element having oneor more walls that enclose an internal region, an opening formed in thebody element that is adapted to receive an extremity of a mammal andallow a portion of the extremity to be positioned within the internalregion, one or more thermal exchanging units that are disposed in theinternal region, and a pump that is adapted to control the pressurewithin the internal region to improve the thermal contact between theone or more thermal exchange units and the surface of the portion of theextremity.

Embodiments of the invention may further provide a device for increasingblood flow and controlling body temperature in a mammal, comprising abody element having one or more walls that enclose an internal region,an opening formed in the body element that is adapted to receive anextremity of a mammal and allow a portion of the extremity to bepositioned within the internal region, one or more thermal exchangingunits that are disposed in the internal region, a manifold having afirst fittings that is in fluid communication with the internal regionand a second fitting that is in fluid communication with a fluid plenumformed in one of the one or more thermal exchanging units, and acontroller system comprising a first pump that is adapted to control thepressure within the internal region when it is in fluid communicationwith the first fitting, a fluid heat changer having a thermal exchangingfluid that is adapted to control the temperature of the one or morethermal exchanging units when it is in fluid communication with the oneor more thermal exchanging units, a pressure sensor that is in fluidcommunication with the internal region, a temperature sensor that isadapted to measure a temperature of the mammal, and a controller that isadapted to control the temperature of the fluid heat exchanging fluidand the pressure of the internal region using inputs received from thetemperature sensor and the pressure sensor, and control the first pump.

Embodiments of the invention may further provide a method of increasingblood flow and controlling body temperature in a mammal, comprisingpositioning an extremity of a mammal in an internal region that isformed using one or more walls of a body element, disposing one or morethermal exchanging units on a surface of the extremity that ispositioned within the internal region, controlling the temperature ofthe one or more thermal exchange units, and adjusting the pressure inthe internal region to cause one of the one or more walls to urge atleast one of the one or more thermal exchange units against the surfaceof the extremity.

Embodiments of the invention may further provide a method of preventingDVT includes providing a flexible lower extremity device to a mammal,the lower extremity device comprising one or more collapsible and pliantbody elements which are capable of expanding from a minimized firstvolume into an expanded second volume for containing a portion of anextremity of a mammal therein and reducing from the expanded secondvolume into a pressurized third volume to conformably enclose theportion of the lower extremity, regulating the temperature of the lowerextremity using the lower extremity device, vasodilating anArteriovenous Anastomoses (AVAs) blood vessel of the lower extremity ofthe mammal, and reducing the constriction of the AVA blood vessel usingthe lower extremity device, thereby increasing blood flow of the lowerextremity and decreasing clotting within the veins. The method canfurther include applying mechanical compression to the lower extremityof the mammal. The method may optionally include reducing the pressureof the chamber of the lower extremity device, such as to vacuum levels.

In a further embodiment, a method of increasing blood flow includesregulating the temperature of one or more extremities of a mammal andexposing the one or more extremities to a vacuum or a reduced pressureenvironment.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a cross-sectional view of one embodiment of an exemplarydevice according to one embodiment of the invention.

FIG. 1B is graph demonstrating the results of increased blood flow usingthe device according to one embodiment of the invention.

FIG. 2A is a perspective view of another exemplary device according toone embodiment of the invention.

FIG. 2B is a close-up partial exploded view of a portion of the thermalexchange unit according to one embodiment of the invention.

FIG. 3A is a perspective view of yet another exemplary device which isnot yet folded nor enclosed according to one embodiment of theinvention.

FIG. 3B is a perspective view of the exemplary device of FIG. 3A whichis folded and enclosed according to one embodiment of the invention.

FIG. 3C is a top view of the exemplary device of FIG. 3A which is foldedand enclosed according to one embodiment of the invention.

FIG. 3D is a side view of the exemplary device of FIG. 3A.

FIG. 4A is an exemplary device which is to be enclosed before a portionof an extremity is disposed according to one embodiment of theinvention.

FIG. 4B is another exemplary device which is enclosed with a portion ofan extremity disposed therein according to one embodiment of theinvention.

FIG. 4C is another exemplary device with a portion of an extremitydisposed and sealed therein according to one embodiment of theinvention.

FIG. 4D is another exemplary device with a large portion of an extremitydisposed and sealed therein according to one embodiment of theinvention.

FIG. 5A illustrates one example of a thermal exchange unit according toone embodiment of the invention.

FIG. 5B illustrates one example of a thermal exchange unit according toone embodiment of the invention.

FIG. 6A is a side view of an exemplary lower extremity device accordingto one embodiment of the invention.

FIG. 6B is a perspective view of an exemplary lower extremity devicewhich is not yet folded nor enclosed according to one embodiment of theinvention.

FIG. 6C is a perspective view of an exemplary lower extremity devicewhich is folded, enclosed and sealed according to one embodiment of theinvention.

FIG. 6D is a side view of an exemplary lower extremity device accordingto one embodiment of the invention.

FIGS. 6E-6F are isometric views of various sized lower extremitiespositioned on the device illustrated in FIG. 6B according to oneembodiment of the invention.

FIG. 6G is a side view of an exemplary lower extremity device accordingto one embodiment of the invention.

FIG. 7 illustrates an exemplary manifold with one or more fittings fortubing's according to an embodiment of the invention.

FIG. 8 illustrates one embodiment of a control unit connected to adevice according to an embodiment of the invention.

FIG. 9 is a graph demonstrating the results of increased blood flowusing the device according to one embodiment of the invention.

FIG. 10 is another graph demonstrating the results of increased bloodflow using the device according to another embodiment of the invention.

FIG. 11 is another graph demonstrating the results of increased bloodflow using the device according to yet another one embodiment of theinvention.

FIG. 12A is a side view of an exemplary device according to oneembodiment of the invention.

FIG. 12B is a plan view of an exemplary device illustrated in FIG. 12Aaccording to one embodiment of the invention.

FIG. 12C is a side view of an exemplary device according to oneembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention include a method and a device forincreasing blood flow and controlling the temperature of a mammal byapplying a desired pressure to extremities of a mammal. The devicegenerally includes one or more collapsible and pliant body elements,capable of expanding from a first volume into an expanded second volumeso the device can receive a portion of an extremity of the mammaltherein and then be reduced from the expanded second volume into apressurized third volume to conformably enclose the portion of theextremity. One or more thermal exchange units can be positioned in theone or more collapsible and pliant body elements. Accordingly, thetemperature of the extremity of a mammal can be regulated by providing aheated or cooled fluid medium or electric thermal energy to the one ormore thermal exchange units. Next, by evacuating the region in which theextremity is enclosed the contact surface area between the extremity ofa mammal and the one or more thermal exchange units is increased, due tothe external atmospheric pressure acting on the pliant body elementsagainst the skin of the extremity of the mammal. The application ofpressure assures that sufficient contact and thermal heat transfer(heating or cooling) is provided to the extremity of the mammal. Bycontrolling the application of pressure to the mammal's extremity thatis positioned within the enclosed region of the one or more collapsibleand pliant body elements skin perfusion can be improved. The pressurethat is applied to the region surrounding the extremity can be adjustedto increase the blood perfusion at the skin surface of the extremity,and also improve heat transfer to the blood and rest of the body. It isbelieved that regulating the pressure in the region around the mammal'sextremity to allow an eternal pressure (e.g., atmospheric pressure) orforce to create a contact pressure between the device components (e.g.,thermal exchange units) and the extremity of about 13.5 mmHg willprovide a desirable increase of blood perfusion. It is also believedthat the exposure of the skin of the extremity to a sub-atmosphericpressure environment can also help the vasodilatation of the vasculaturein the mammal's extremity. The vasodilatation of the vasculature mayalso help to increase the thermal exchange between the one or morethermal exchange units and the mammal's extremity.

The extremity can be any kinds of the extremity of a mammal, such as anarm, a hand, a forearm, a forearm with an elbow, a hand with a wrist, alimb, a foot, a leg, a calf, an ankle, toes, etc., where ArteriovenousAnastomoses (AVAs) are located and/or when increased blood flow isdesired. Arteriovenous Anastomoses (AVAs), which are connected toarteries and veins, are specialized blood vessels located primarily inthe palms and fingers of the hands, the soles and toes of the feet, thecheeks, and the ears, etc. It is recognized that the device describedherein may be adapted for use with other extremities that havevasculature structures suitable for the increasing blood flow methodsdescribed herein. Regulating the temperature of the mammal's extremitymay include elevating, cooling, and/or maintaining the mammal'stemperature. The mammal may be a human or other mammal. People at highrisk of DVT, PE and other conditions, such as edema, wound swelling,venous stasis ulcers, diabetic wounds, decubitous ulcer, orthopedicsurgery patients, spinal cord injured individuals, among others, canbenefit from the invention.

According to one or more embodiments of the invention, devices andmethods are provided to intervene thermal maladies (e.g., hypothermiaand hyperthermia, etc.), to regulate the temperature of the extremity ofa mammal when the thermoregulatory system of the mammal is compromised(e.g., by general anesthesia, local anesthesia, trauma, post-surgeryconditions, or other factors), and/or to prevent deep vein thrombosis(DVT), pulmonary embolism (PE), and other diseases. The devices andmethods as described herein are tested to be able to increase blood flowin the extremity of the mammal, which may include an appendage.Experiments performed on humans that have diabetes indicate that optimalpressure to increase blood flow could be about 13-14 mmHg, but thatpressures between 1 and 80 mmHg, and more preferably 3 and 40 mmHg andmore preferably 5 and 20 mmHg can increase blood perfusion. Pressures ofapproximately 14 mmHg combined with appropriate heat can increase bloodflow, as a percent per minute of the volume of the appendage (in thiscase an arm) from a base level of between about 4% per minute to anincreased level of about 8% per minute. The pressure applied to the skinby the device can be used to increase blood flow, which can beaccomplished by a variety of methods including, but not limited to usingatmospheric pressure to collapse a bag that has been evacuated or bypressurizing, or inflating, a cuff that encompasses a significantportion of appendage (FIG. 6G). Some results and embodiments arediscussed below.

In one embodiment, a device for increasing blood flow and preventingdeep vein thrombosis (DVT) is provided to a mammal's extremity by usingatmospheric pressure outside the enclosed extremity to increase thesurface area of the contact between the skin of the mammal's extremityand one or more thermal exchange units to improve profusion, and byregulating the temperature of the mammal's extremity by controlling thetemperature of the thermal exchange units. In this case, the externalatmospheric pressure is used to press the one or more thermal exchangeunits against the mammal's extremity to provide as much thermal exchangeas possible, and increasing the blood flow of the mammal's extremity. Inparticular, the invention provides a non-invasive, convenient apparatusfor efficiently adjusting the temperature, applying vacuum, and/orapplying compression pressure or forces, to the mammal's extremity toincrease blood flow, promote venous blood return, prevent clots in theveins, and prevent DV, among others.

FIG. 1A is a cross-sectional view of one embodiment of a device 100 thatis used to increasing blood flow by transferring heat to a mammal'sextremity. The device transfers heat to and/or from a mammal'sextremity, such as an arm, a hand, a forearm, a forearm with an elbow, ahand with a wrist, a limb, a foot, a leg, a calf, an ankle, toes, etc.,where AVAs are located to provide an improved and efficient control ofthe patients temperature, and blood flow in the extremity. FIG. 1Billustrates plots of the core temperature of a patent as a function oftime using various different methods to increase the temperature of thepatient's core. Curves P1, P2 and P3 illustrate the published resultsreceived using conventional techniques, such as convective heat transferprocesses that exchange heat with the skin of the patient by deliveringa flow of heated or cooled air. Curves C1 and C2 illustrate the resultsreceived using the devices discussed herein, for example, device 100illustrated in FIG. 1A. One characteristic feature of the conventionalschemes illustrated by the curves P1, P2 and P3 is the unwanted andimmediate decrease in temperature of the patient for a period of timebefore a minimum temperature 195 is reached, and the patient'stemperature finally starts to increase. It is believed that the initialdecrease in temperature found using conventional convective heattransfer techniques illustrated in curves P1, P2, and P3 is undesirableand uncomfortable to the patient, since it generally causes or doesn'tquickly eliminate shivering of the patient. In contrast, as shown incurves C1 and C2, the devices discussed herein will have thecharacteristic of a generally increasing core temperature from the startand doesn't have the inefficient and uncomfortable effect found incurrent conventional devices, due to the novel method of enclosing thepatient's extremity, adjusting the pressure surrounding the extremitywithin the enclosure, increasing blood perfusion by controlling thecontact pressure, and improving the thermal contact with a thermal heatexchanging device (e.g., conductive heat transfer), as discussed below.

FIG. 1A is a cross-sectional view of one embodiment of a device 100having one or more thermal exchange units 120A, 120B. The device 100includes an opening 112 formed in one or more body elements 110 that isused to enclose and receive a portion of an extremity 130 of a mammal.The device 100 may also contain a sealing element 140 that is attachedto the opening 112, which is used to form a seal around the extremity130. The enclosed extremity 130 positioned within the internal region113 of the device 100 can then be evacuated to allow the atmosphericpressure external to the one or more body elements 110 to urge the oneor more thermal exchange units 120A, 120B against the extremity 130 toprovide a desired thermal exchange. Also, by enclosing the extremity 130the thermal environment formed around the extremity can help to improvethe control of the temperature and heat exchange between thermalexchange units and the extremity.

The body element 110 is generally designed so that it will occupy aminimum amount of space, or volume, so that it can be easily andconveniently folded, stored, or shipped. The body element 110 isgenerally capable of being expanded from a minimized volume into anexpanded volume for containing a portion of an extremity of a mammaltherein. Under a pressurized condition, the volume or space of the bodyelement 110 may be reduced from the expanded volume into a pressurizedvolume or space, such as a volume that conformally encloses the portionof the extremity 130. It is generally desirable to use a body element110 that is flexible enough to allow the pressure applied to each andevery portion of the extremity 130 enclosed inside the device 100 to beevenly and equally distributed. In general, the minimized volume and theexpanded volume are maintained under atmospheric pressure.

Embodiments of the invention provide subjecting portions of an extremityof a mammal to a reduced pressure environment, preferably under vacuumor a negative pressure to increase contact surface area for thermalregulation, and adjusting the temperature of the extremity of themammal, thereby increasing blood flow. Under a reduced pressure insidethe device 100, the portions of the body element 110 are pressed againstextremity 130. The pressure inside the internal region 113 of thepressurized volume of the body element 110 of the device 100 can beregulated to a level lower than atmospheric pressure, such as a pressurelevel of about 0 mmHg to about −80 mmHg by use of a pump 163 (e.g.,mechanical pump). In another example, it is desirable to regulate thepressure in the internal region 113 to a pressure between about −10 mmHgto about −14 mmHg. In another example, it is desirable to regulate thepressure in the internal region 113 to a pressure between about −10 mmHgto about −13.5 mmHg.

The body element 110 is comprised of a collapsible and pliant material,including but not limited to, urethane, polyurethane, polypropylenes,polystyrenes, high density polyethylene's (HDPE), low densitypolyethylene's (LDPE), poly(vinyl chloride), rubbers, elastomers,polymeric materials, composite materials, among others. For example, thebody element 110 can be made of disposable low cost materials. Thecollapsible and pliant material may comprise any suitable flexiblematerial, for example, gas permeable thermoplastics, elastomericmaterials, such as C-FLEX™ from Consolidated Polymer Technologies, Inc.(Largo, Fla.), DynaFlex from GLS Corporation (McHenry, Ill.), materialsavailable from Argotec (Greenfield, Mass.), and other elastomericmaterials with similar properties. In one embodiment, the collapsibleand pliant material comprises a material that is temperature resistant.The body element 110 can also be made of a biocompatible or hypoallergic material (and therefore safe for contact with the skin of amammal), alternatively, the body element can be made of a transparent orsemi-transparent material that allows viewing of the extremity 130positioned therein. As another example, the body element 110 may be madeof materials that may be sterilized via autoclaving or ethylene oxidesterilization. This is especially important if the device is used duringsurgery where sterile conditions are very important. The thickness ofthe collapsible and pliant material is not limited as long as it cansustain the pressurized conditions when the device 100 is used. In oneexample, a urethane material having a thickness from about 1.5 mils toabout 12 mils can be used to pliantly conform to the shape and size ofthe portion of the extremity 130 contained therein. In general, thethickness of the collapsible and pliant material is not limited as longas it is compliant enough to substantially conform to the extremity andcan sustain the desired pressurized conditions when the device 100 is inuse.

The one or more thermal exchange units 120A, 120B can be attached to oneor more portions of the body element 110 and adapted to contact theportion of the extremity 130 under pressurized conditions and toincrease, reduce, or maintain the temperature of the extremity 130received therein. The thermal exchange unit 120A, 120B can bepermanently or detachably placed inside the device 100 to providethermal exchange for the extremity 130 received therein. Examples ofsome exemplary thermal exchange units 120A, 120B are illustrated andfurther discussed in conjunction with FIGS. 5A-5B.

A thermal-exchange fluid medium, such as heated fluid, heated air,cooled fluid, or cooled air, etc., can be provided from a fluid source161 into the thermal exchange units 120A, 120B via one or more fluidsupply lines 124 and out of the device 100 via one or more fluid returnlines 122. The temperature of the one or more thermal exchange unitspositioned in the device 100 may also be controlled by use of anelectric pad, fluid type heat exchanging device, or any other suitablethermal exchange units, that are used individually or in combination.Thermal energy can be transferred from the thermal exchange unit to theextremity 130 during heating or from the extremity 130 to the one ormore thermal exchange units during the process of cooling the extremity130. For example, the thermal exchange units 120A, 120B may be a fluidheating pad having, for example, heated water delivered there throughusing a recirculation type heat exchanging system. As another example,the thermal exchange units 120A, 120B may be a pad having chemicalstherein for heating or cooling. Alternatively, the thermal exchangeunits 120A, 120B may include an electric pad, as described in detail inco-pending U.S. provisional patent application Ser. No. 60/821,201,filed Aug. 2, 2006, which is incorporated by reference herein.

Good contact with the thermal exchange units 120A, 120B is important inmaximizing thermal transfer to the extremity 130. Also, it is desirableto assure that the thermal exchange unit(s) will not loose contact theextremity 130 through normal jostling or positioning of the patient.Also, optimal contact and efficient thermal exchange between the thermalexchange units and the extremity 130 can be compromised when portions ofthe extremity 130 become arched or deformed due to the pressuredifferential acting on the extremity and the exterior of the device 100when the internal region 113 is evacuated. The contact force caused bythe pressure differential is approximately equal to the contact surfacearea of the thermal exchange unit against the extremity 130 times thepressure differential. For example, the pressure differential may beapproximately three pounds. In one embodiment, the collapsible andpliant body elements of the device helps to assure that sufficientcontact between the thermal exchange units 120A, 120B and the extremity130 is maintained if the extremity becomes arched or deforms. Thesurface pressure created by the external atmospheric pressure urges thethermal exchange units 120A, 120B against the extremity 130. As such, byapplying a surface pressure to the extremity 130 thermal energy can bemore evenly distributed to the extremity 130.

Accordingly, the materials of the body element 110 and the thermalexchange units 120A, 120B are made of a flexible material, which can bepliant and easily collapsible to conform into the shape of the extremityand securely surround and enclose the portion of the extremity 130 toprovide good contact between the surfaces of the extremity 130 and thethermal exchange units 120A, 120B (or the body element 110). Thematerial for the thermal exchange units 120A, 120B and the body element110 are comprised of collapsible and pliant material to enhance thesurface contact between the thermal exchange units 120A, 120B and theextremity 130. The material of the body element 110 thus may collapseagainst the thermal exchange units 120A, 120B due to the sub-atmosphericpressure or a vacuum pressure level achieved in the internal region 113of the device 100.

The body element 110 may include one or more apertures for attachingvarious fluid ports or pressure ports, such as a pressure port 116, apressure sensing port 118, the fluid supply line 124, and the fluidreturn line 122. Accordingly, one or more thermal exchange supply lines(e.g., item 124) and one or more thermal exchange return lines (e.g.,item 122) can be connected to one or more thermal sources (e.g., fluidsource 161) through the one or more apertures formed in the body element110. In one embodiment, a manifold 114 may be formed or disposed on aportion of the body element 110 to provide the connections between thevarious external components to the device 100. The pressure sensing port118, the pressure port 116, the fluid supply line 124, and/or the fluidreturn line 122 may be covered by protective sheaths. In one aspect, themanifold 114 contains a pressure port 116, a pressure sensing port 118,the fluid supply line 124, and the fluid return line 122 that areconnected to various kinds of tubing and/or connectors to connect thevarious external components in the device 100 to the various componentsor regions positioned within the internal region 113 of the device 100.The manifold 114 may be connected to the one or more apertures, the oneor more pressure ports, and the one or more thermal exchange units ofthe device 100. The position of the apertures for the fluid ports orpressure ports can be located near any convenient portions of the bodyelement 110 and can be close to the manifold 114 or grouped together forpassing through the body element 110 via a single aperture. One exampleof a manifold 114 is shown in FIG. 7 to incorporate quick connecting anddisconnecting fittings.

The sealing element 140 is formed on a portion of the opening 112 andadapted to seal the portion of the extremity 130 when placed inside theinternal region 113 of the body element 110 to allow a pressure to beapplied to the extremity 130. The sealing element 140 may be adapted toallow a pressurized volume to be formed so that an even and equalpressure is applied on each and every position for the portion of theextremity 130 of the mammal. The sealing element 140 is generally sizedand used to seal the opening according to the size of the portion of theextremity 130 of the mammal. The sealing element 140 may be made of amaterial that is biocompatible (and therefore safe for contact with theskin of a mammal) and capable of producing an airtight seal. In oneembodiment, the sealing element 140 is detachably attached to theopening 112. In another embodiment, the sealing element 140 is comprisedof a disposable material, such as a disposable liner or an insertmaterial. For example, the material of the sealing element 140 may behydrogel, a sticky seal material, polyurethane, urethane, among others.One example of the material is hydrogel. Another example is a PS seriesthermoplastic polyurethane from Deerfield Urethane, Inc. Disposablesealing materials may be manufactured and packaged such that they aresterile before use and/or hypoallergenic to meet health and safetyrequirements. The sealing element 140 may include an air permeableportion and/or made of a permeable membrane material or a breathablematerial to permit the flow of air, etc. Examples of breathablematerials are available from Securon Manufacturing Ltd. or 3M Company.The permeable portion may be positioned near any portion of the bodyportion to provide permeable outlets, allowing the vacuum to have theproper effect on the extremity 130 and providing a barrier keeping thedevice 100 from contamination for the comfort of the patient.

The pressurized volume defined by the body element 110 and sealingelement 140 is formed by applying a negative pressure to the pressureport 116, which can be connected to a pump 163, for reducing thepressure of the internal region 113 inside the device 100. In addition,the pressure level inside the chamber 150 can be monitored by a vacuumsensor 162 placed inside the pressurized volume or be in fluidcommunication or fluidly attached to the pressure sensing port 118. Oneor more pressure ports may also be positioned between the at least onepump 163 and the body element 110.

During operation, the sealing element 140 is wrapped around the portionof the extremity 130 of the mammal top to seal the opening 112. In oneembodiment, the air inside the device 100 is pumped out via a pressureport 116 connected to a pump 163 to provide a vacuum or sub-atmosphericenvironment in the internal region 113 of the device 100. It isrecognized that the sealing element 140 is one example of a seal thatmay be used with the device 100, and in some cases it may be desirablenot to use a seal at all. However, it is generally desirable provide aseal to reduce the leakage and thus reduce the amount of air that mustbe continuously removed from the apparatus during the use of the device100. However, a sealing element 140 that exerts too much force on theextremity 130 may reduce or eliminate the return blood flow to the body,thus reducing the effectiveness of the device, and potentially creatingadverse health effects. The sealing element 140 may also be attached tothe device 100 with mechanical fasteners or other fastening units, suchas one or more mating rings which can snap into the device 100. Anotherexample includes the use of a tape with a removable liner, such as 3Mremovable tapes, etc., which can be removed when ready to use.

In one embodiment, the sealing element 140 is a single use seal. Inanother embodiment, the single use sealing element 140 is attached tothe device 100, and the device and the sealing element 140 are disposedof after a single use. In still another embodiment, the sealing element140 may be removed from the device 100 and the device may be usedrepeatedly with another sealing element.

In one embodiment, the sealing element 140 may comprise a strip ofreleasable adhesive tape ranging from 0.5 inches to 6 inches in width,e.g., a width large enough to cover the bottom of the extremity 130. Thesealing element 140 may comprise an adhesive face and a backing portion.The sealing element 140 is generally long enough that when wrapped endover end around the edge of the opening 112, an overlap of about 0.5inches or larger, such as about 2 inches, is present. The overlap ispreferably not to encourage the user to wrap the sealing element 140around the extremity too tightly and thus create a modest vacu-sealingforce, e.g., less than 20 mm Hg. The material of the sealing element 140may comprise a releasable adhesive material for attachment to a mammalextremity in some portion and a more permanent adhesive in otherportions thereof for attaching the sealing element 140 to the device100. The releasable adhesive material may be any of a wide variety ofcommercially available materials with high initial adhesion and a lowadhesive removal force so that the sealing element 140 does not pull offhair or skin and create pain when it is removed. For example, thereleasable adhesive may be a single use adhesive. In addition, theadhesive material may be thick and malleable so that it can deform orgive, in order to fill gaps. Adhesives with water suspended in a polymergel, e.g., a hydrogel, are generally effective. One example of such anadhesive is Tagaderm branded 3M adhesive (part No. 9841) which is a thin(5 mm) breathable adhesive that is typically used for covering burns andwounds. Another example is an electrocardiogram (EKG) adhesive such as3M part No. MSX 5764, which is a thicker adhesive (25 mm). The sealingelement 140 should fasten such that there is no leakage of the vacuum.

In one embodiment, the sealing element 140 has a backing that may be athin, non-elastic, flexible material. The backing supports the adhesiveand keeps it from being pulled into the opening 112 when the internalregion 113 is evacuated. The backing also allows the adhesive to conformto both the shape of the extremity 130 and the shape of the opening 112,as well as to fold in on itself to fill gaps that may be present in thevacu-seal around the extremity 130. Furthermore, the backing preventsthe adhesive from sticking to other surfaces. Commercially availablepolyethylene in thicknesses up to about 10 millimeters may be used forthe backing. Polyethylene that is thicker than about 10 millimeters maylimit the adhesive's ability to fold on itself and fill in gaps. Thebacking may also comprise any polymer that may be fabricated into athin, non-elastic, flexible material. In one embodiment, the sealingelement 140 comprises a backing has an adhesive disposed on two opposingadhesive faces to allow it to be attached to the body element 110 andthe extremity 130. For example, 3M EKG adhesive products MSX 5764contains a supportive backing in between multiple layers of adhesive.Multiple layers of backing can also be used to provide support for thesealing element 140.

The opening 112 of the device is preferably close to the size of thepatient's extremity to minimize the difference in dimensions that thesealing element 140 must cover. The smallest opening size that willaccommodate the range of extremity dimensions, such as foot sizes ispreferred. Minimizing the opening size reduces the force on theextremity 130, which is approximately equal to the area of the opening112 times the pressure differential. The sealing element 140 istypically able to be formed of different sizes to accommodate extremitysizes down to the size of a small adult and up to various sizes of alarge adult. For example, multiple opening sizes, such as small, medium,and large may be used to accommodate a wider range of foot sizes.

Alternatively, the opening 112 may be adapted to contract within a sizerange of the extremity 130 without constricting blood flow to furtherminimize this force and make the sealing process by the sealing element140 easier. For example, one or more strings may be used to tighten theopening 112 to the extremity 130. In another embodiment, externalbuckles, Velcro fasteners, and straps, among others, may also be used tosurround the opening 112 of the device 150 and secure the opening 112around the extremity 130.

In addition, one or more portions of the body element 110 may be madefrom transparent materials such that the functioning of the device andthe condition of the extremity 130 may be monitored during use of thedevice. In an alternative embodiment, the body element 110 may bedivided into two or more body sections to be assembled into the device100 and secured by one or more fastening units, such as Velcrofasteners, or conventional snaps.

The device 100 may further include a control system 164 that contains acontroller 160 that is connected to various parts of the device 100,including the pump 163 and vacuum sensor 162 connected to one or more ofthe pressure ports, the fluid source 161 connected to one or more of thefluid lines connected to the one or more thermal exchange units. Thecontroller 160 may be adapted to regulate the functions and processperformed by the device 100, including adjusting the fluid flow in andout of the thermal exchange units 120A, 120B, regulating the temperatureof the thermal exchange units 120A, 120B, monitoring the pressure levelinside the device 100 via one or more vacuum sensors 162, adjusting thepump 163 speed and the vacuum level inside the device 100, andmonitoring the temperature of the extremity 130 received therein, amongothers. In one embodiment, the devices described herein may include anin-use sensor indicating that the device is in use (e.g., vacuumswitch). In addition, the in-use sensor and/or controller 160 mayindicate how many times the devices have been used.

According to an embodiment of the invention, the device can be used incombination with a mechanical compression device or a pressurizedcompression device to help pump blood through the patient's body.Alternatively, the device 100 can itself be modified to include one ormore pressure-applying gas plenums positioned within or attached to thebody element 110 in order to apply a compression force or positive gaspressure on the extremity 130 of a mammal, in addition to controllingthe extremities temperature by delivering a thermally controlled fluidto the one or more fluid exchange units that are in contact with theextremity.

FIG. 2A is a perspective view of another example of a device 200according to one or more embodiments of the invention. The device 200may include a thermal exchange unit 220, a pressure port 216, a pressuresensing line 218, a fluid supply line 224, a fluid return line 222, anopening 112 for the extremity to be enclosed therein, and a sealingelement 140. A manifold 214 may be formed for providing the connectionbetween the various fluid ports or pressure ports, such as the pressureport 216, the pressure sensing line 218, the fluid supply line 224, andthe fluid return line 222, and other external components.

In one embodiment, the thermal exchange unit 220 that is permanentlyattached to the device 200 and composed of a collapsible and pliantmaterial, including but not limited to, urethane, polyurethane,elastomers, polypropylenes, polystyrenes, high density polyethylene's(HDPE), low density polyethylene's (LDPE), poly(vinyl chloride),rubbers, polymeric materials, composite materials, among others. Thethermal exchange unit 220 is generally designed to allow a fluid mediumto be delivered there through to exchange heat with an extremity. As aresult, there is no need for a separate body element (see item 110 inFIG. 1A) and thermal exchange unit 220 can be used to enclose theextremity 130 by forming a internal region 213, which can be evacuated.In addition, the body of the thermal exchange unit 220 is capable offorming into a minimized volume for folding, storage, and/or shipping.The space enclosed by the thermal exchange unit 220, or internal region213, can also be expanded so that the extremity 130 can be disposedtherein. The internal volume 213 of the thermal exchange unit 220 can bereduced under a pressurized condition to conformably apply even andequal pressure on the portion of the extremity 130 disposed inside thedevice 200.

The thickness of the material for the thermal exchange unit 220 is notlimited as long as it is compliant enough to substantially conform tothe extremity and can sustain the pressurized conditions when the device200 is used and the fluid medium can be delivered therein. For example,a urethane material having a thickness of from about 1.5 mils to about12 mils can be used to pliantly conform to the shape and size of theportion of the extremity 130 contained therein. Another possiblematerial may include NTT-6000, which is a polyether polyurethanemanufactured using USP Class V1 compliant materials. The NTT-6000material can be a 2 mil gage material that is a natural color and isavailable from American Polyfilm, Inc. Branford, Conn. NTT-6000.Optionally, the thermal exchange unit 220 may be connected to theopening 112 through a body element 242. Alternatively, the body of thethermal exchange unit 220 can directly form the opening 112 without theuse of an additional body element 242. Additionally, the device 200 mayinclude temperature sensors to measure the fluid in and out of thethermal exchange units 200 and to measure the surface temperature of theextremity 130, such as a patient's body surface temperature.

The device 200 may further include a control system 164 having acontroller 160 connected to various parts of the device 200, includingthe pump 163 and vacuum sensor 162 connected to one or more of thepressure ports, the fluid source 161 connected to one or more of thefluid lines connected to the one or more thermal exchange units. Thecontroller 160 may be adapted to regulate the functions and processperformed by the device 200, including adjusting the fluid flow in andout of the thermal exchange units 220, regulating the temperature of thethermal exchange units 220, monitoring the pressure level inside thedevice 200 via one or more vacuum sensors 162, adjusting the pump 163speed and the vacuum level inside the device 200, and monitoring thetemperature of the extremity 130 received therein, among others.

In one embodiment, as shown in FIG. 2B, the thermal exchange unit 220 isformed by bonding or sealing two layers (e.g., layers 231 and 232) of acollapsible and pliant material together to form a composite element 230having a fluid plenum 233 formed between the bonded and sealed layers toallow a heat exchanging fluid to be delivered from the fluid source 161there through. FIG. 2B is a partially exploded cross-sectional view of aportion of the thermal exchange unit 220 according to an embodiment ofthe invention. The layers 231 and 232 can be sealed (e.g., seal 234) byuse of a heat sealing, gluing, or other conventional compliant layerbonding technique. Then two or more composite elements 230 can then bebonded together (see “A” in FIG. 2B) at a sealing region 235, using aheat sealing, gluing, or other conventional technique, to form theinternal region 213 in which the extremity 130 can be placed. The layers231 and 231 may composed of a collapsible and pliant material, includingbut not limited to, urethane, polyurethane, polypropylenes,polystyrenes, high density polyethylene's (HDPE), low densitypolyethylene's (LDPE), poly(vinyl chloride), rubbers, elastomers,polymeric materials, composite materials, among others.

In one embodiment, a plurality of dimples 240 are formed between thelayers 231 and 231 to form a stronger composite elements 230 that willnot dramatically expand when a heat exchanging fluid is delivered fromthe fluid source 161 to the thermal exchange unit 220. In oneembodiment, a separating feature 236 is formed through a region of thecomposite element 230 to allow fluid delivered from the fluid supplyline 224 to flow through the fluid plenum 233 and around the separatingfeature 236 before the fluid exits the thermal exchanging unit 220 andenters the fluid return line 222. The separating feature 236 may beformed by RF welding, thermal sealing, gluing, or bonding the layers 231and 231 together. In one embodiment, a composite element 230 is formedon either side, or wraps around, the extremity 130 in the device 200 toprovide improved thermal contact and heat exchanging properties.

FIG. 3A is a perspective view of a device 300 in its opened and unfoldedposition according to one embodiment of the invention. FIGS. 3B, 3C, 3Dillustrate a perspective view, a top view, and a side view of the device300 which is folded and enclosed according to one embodiment of theinvention. The device 300 may include a singular body element being flatand unfolded. Alternatively, the device 300 may include a first bodyelement 310A and a second body element 310B, as shown in FIG. 3A. Thefirst body element 310A and the second body element 310B can be folded,for example, through the direction of an arrow A, to form the opening112 (FIG. 3B) and to enclose a portion of the extremity 130 of a mammal.

The first body element 310A and the second body element 310B may becomprised of the same material as the body element 110 of the device100. The size of the opening 112 may be sealed and reduced by a sealingelement 342. The material of the sealing element 342 may be the samematerial as the sealing element 140 discussed above. In addition, thedevice 300 generally further includes one or more thermal exchange units320A and 320B capable of containing a thermal-exchange fluid mediumtherein. Optionally, the first body element 310A and the second bodyelement 310B may be connected to the opening 112 through a body element343. Alternatively, the body of the first body element 310A and thesecond body element 310B can directly form the opening 112 without theuse of an additional body element 343. In one embodiment, the first bodyelement 310A, the second body element 310B, and the additional bodyelement 343 are formed from a collapsible and pliant material, includingbut not limited to, urethane, polyurethane, polypropylenes,polystyrenes, high density polyethylene's (HDPE), low densitypolyethylene's (LDPE), poly(vinyl chloride), rubbers, elastomers,polymeric materials, composite materials, among others.

In operation the device 300 is folded so that the edges 350 of the firstbody element 310A and the second body element 310B may be enclosed by anenclosing clip 352, for example, through the direction of an arrow B(FIG. 3B), such that the opening 112 is formed for the portion of theextremity to be inserted therein. The mechanism by which the enclosingclips 352 can be used to enclose the edges 350 of the first body element310A and the second body element 310B may vary and include fasteners,zippers, snaps, buttons, hydrogel coated tabs, conventional tape typematerials, hook/loop type systems, among others. For example, the edges350 of the first body element 310A and the second body element 310B maybe reinforced such that the edges 350 can stayed together via theenclosing clip 352 and hold the portion of the extremity 130 in placeuntil vacuum or reduce pressure is applied to the internal region 313formed between the first body element 310A and the second body element310B.

Further, a generalized port 325 can be used to bundle up the variousfluid ports and pressure ports together. The generalized port 325 can beused to fluidly or electrically connect the controller 160 (see FIG.3C), the fluid source 161, vacuum sensor 162, and/or a pump 163 to thevarious components found in the internal region 313 of the device 300.For example, the generalized port 325 may include a pressure port 316, apressure sensing line 318, a fluid supply line 324, and a fluid returnline 322 therein. The generalized port 325 may also be used to connectto one or more compression air plenums for applying a compressionpressure on the portion of the extremity 130.

FIG. 4A is another example of a device 400 according to one embodimentof the invention that is in an “open” position to receive an extremity130 (See FIG. 4B). FIG. 4B illustrates the device 400 which isconfigured to enclose a portion of the extremity 130 disposed thereinaccording to one embodiment of the invention. The device 400 includes abody element 410 which can be folded and/or rolled up and down to formthe opening 112 to enclose a portion of the extremity 130 of a mammal.The body element 410 may be comprised of the same material as the bodyelement 110 of the device 100. In addition, the device 400 may furtherinclude one or more thermal exchange units 420A and 420B capable ofcontaining a thermal-exchange fluid medium therein.

Referring to FIG. 4B, the size of the opening 112 formed when theextremity 130 is enclosed within the device 400, may be sealed by use ofa sealing element 440. The material of the sealing element may be thesame material as the sealing element 140.

In operation, the device 400 is unfolded and folded according to thedirection of an arrow C to cover and enclose the thermal exchange units420A and 420B and the extremity 130. FIG. 4B illustrates the device 400in an enclosed configuration. In one embodiment, during the process ofenclosing the extremity 130, the edges 450 of the thermal exchange units420A and 420B may be urged together by one or more enclosing clip 452and the opening 112 can be formed for the portion of the extremity 130to be inserted therein. The mechanism by which the enclosing clips 452can be used to enclose the edges 450 may vary and include fasteners,zippers, snaps, hydrogel coated tabs, conventional tapes, buttons, andhook/loop type systems, among others. For example, the edges 450 of thethermal exchange units 420A and 420B may be reinforced such that theedges 450 can be sealed and snapped-locked tightly by the enclosingclips 452. Further, a generalized port 425 can be used to bundle up thevarious fluid lines and pressure lines together that are connected tothe controller 160, the fluid source 161, vacuum sensor 162 an/or a pump163 (FIG. 4B). In addition, a manifold 414 may be used to help connectand disconnect the various fluid ports and pressure ports between thegeneralized port 425 and the thermal exchange units 420A and 420B.

FIGS. 4C and 4D illustrate examples of the device 400, such as device400A (FIG. 4C) and device 400B (FIG. 4D), with a portion of an extremity130 disposed and sealed therein according to one or more embodiments ofthe invention. The extremity 130 to be enclosed by the device 400A canbe a hand, as shown in FIG. 4C, in which the device 400A is shaped likea mitten or a glove. In this configuration, the one or more thermalexchange units 420 are sized to heat the desired area of the extremity130 that is positioned within the body element 410. The internal region413 of the device 400A can be evacuated and the thermal exchange unit(s)420 can be temperature regulated by use of the controller 160, fluidsource 161, vacuum sensor 162 an/or a pump 163, which is schematicallyillustrated in FIG. 4C. While only a single thermal exchange unit 420 isshown n FIGS. 4C and 4D, this configuration is not intended to belimiting to the scope of the invention, and thus two or more thermalexchange units 420 may be positioned around various parts of theextremity 130 to improve perfusion.

As shown in FIG. 4C, alternatively, the extremity 130 enclosed in thedevice may be a large portion of an arm, or other appendage. The device400B can be shaped like an elongated glove to conformably enclose thearm. The increased surface area of the body enclosed and temperaturecontrolled by use of the thermal exchange unit(s) 420 shown in FIG. 4Dversus FIG. 4C may be useful to help more rapidly and/or easily controlthe subjects body temperature during use.

Referring to FIGS. 4C and 4D, a generalized port 425 can be used tobundle up various fluid ports and pressure ports together and connectedto the controller 160, the fluid source 161, vacuum sensor 162 an/or apump 163.

FIG. 5A illustrates one example of the thermal exchange unit 120, suchas the thermal exchange units 120A, 120B, 220, 320A, 320B, and 420discussed herein, according to one embodiment of the invention. Thethermal exchange unit 120 includes a thermal exchange body 546 havingsides 546A and 546B. One side (e.g., side 546B) of the thermal exchangebody 546 includes a plurality of thermal contact domes 548 that have athermal contact surface 547 that can be applied to a portion of theextremity 130. The diameter of the thermal contact surfaces 547 and theshapes or sizes thereof can vary such that the sum of the total area ofthe thermal contact surfaces 547 can be maximized. The thermal exchangeunit 120 may further include the thermal fluid supply line 124 and thethermal fluid return line 122 connected to a thermal fluid source (e.g.,fluid source 161 FIG. 1A) for circulating a thermal fluid medium throughthe thermal exchange body 546 of the thermal exchange unit 120.

The material of the thermal exchange body 546 may be any flexible,conductive and/or durable material, for example, any of the materialssuitable for the body element 110. In one embodiment, the thermalexchange body 546 is made of a flexible material which can easilyconform to the shape of the extremity 130. In another embodiment, thethermal contact domes 548 are made of a rigid material to provide rigidcontacts to the extremity 130.

In addition, the material of the thermal contact domes 548 may be amaterial which provides high thermal conductivity, preferably muchhigher thermal conductivity than the material of the thermal exchangebody 546. For example, the thermal contact domes 548 may be made ofaluminum, which provides at least 400 times higher thermal conductivitythan plastics or rubber materials. In one embodiment, the thermalexchange unit 120 can be formed and assembled through RF welding. Inanother embodiment, the thermal exchange unit 120 may be formed andassembled through injection molding. There are many possible ways todesign and manufacture the thermal exchange body 546 to provide aflexible thermal exchange unit that does not leak. In one embodiment,the thermal exchange unit 546 is formed by bonding a compliant materialthat is sealed using conventional techniques at a joint 549.

In one embodiment, the thermal exchange unit is formed from layers ofseveral materials bonded together to form internal fluid flow paths forthermal fluids to be delivered therein. The multiple layer configurationmay result in uneven surfaces, due to the presence of the internal fluidflow paths. The resulting bumpy surfaces may provide less contact,thereby reducing surface area needed for maximum thermal transfer. Thethermal exchange body 546 may also be formed using a low thermalconductivity material, such as polyurethane. To prevent these problemsfrom affecting the results, the thermal exchange body 546 may be coveredby one or more backing sheets such that a flat and even contact is madeto the extremity. In addition, the backing sheet can be made of highthermal conductive material to provide high thermal conductivity betweenthe thermal exchange unit 120 and the extremity. For example, thebacking sheets may be made of a thin metal sheet, such as aluminum (likea foil) or other metal sheets. In general, aluminum or other metalmaterials may provide higher thermal conductivity than plastics orrubber, e.g., at least 400 times higher.

FIG. 5B illustrates another embodiment of the thermal exchange unit 120that is formed using two layers of a compliant material 541 that aresealed at the edge region 535 by use of an RF welding, thermal sealing,gluing or other bonding process to form a sealed main body 542. The mainbody 542 may have an inlet port 544 and an outlet port 543 that are influid communication with the fluid source 161, and the fluid supply line124 and fluid return line 122, respectively. The region formed betweenthe two layers of the compliant material 541 is thus used as a fluidplenum that can receive (see arrow A₁) and then exhaust (see arrow A₃)the thermal fluid medium from the fluid source 161. In one embodiment, aseparating feature 536 is formed in the thermal exchange unit toseparate the fluid delivered into the inlet port 544 and the outlet port543, and thus allow the thermal exchanging fluid to follow a desirablepath through fluid plenum to optimize and/or improve efficiency of theheat transfer process. In one example, the fluid flow path sequentiallyfollows the arrows A₁, A₂ and A₃. The separating feature 536 can beformed in the sealed main body 542 by RF welding, thermal sealing,gluing or other bonding process to bond the two layers of the compliantmaterial 541 together. In one embodiment, a plurality of dimples 540 areformed between the layers of compliant material 541 in the sealed mainbody 542 by RF welding, thermal sealing, gluing or other bonding processto form a structure that will not expand when a heat exchanging fluid isdelivered to the internal region of the sealed main body 542. In oneembodiment, the thermal exchange unit 120 is formed and assembledthrough RF welding or thermal sealing techniques. In another embodiment,the thermal exchange unit 120 may be formed and assembled throughinjection molding. In one embodiment, the thermal exchange unit 120illustrated in FIG. 5B is formed from a pliant material, including butnot limited to, urethane, polyurethane, polypropylenes, polystyrenes,high density polyethylene's (HDPE), low density polyethylene's (LDPE),poly(vinyl chloride), rubbers, elastomers, polymeric materials,composite materials, among others.

Alternatively, one or more thermal exchange units 120 may be an electricpad having one or more electric wires connected to a power source. Forexample, the power source may be a low voltage DC current power source.In addition, the one or more thermal exchange units may include athermocouple to monitor the temperature and a thermo switch toautomatically shut off the electric power when the temperature of theelectric pad passes a safety level.

The thermal exchange units as described herein (e.g., reference numerals120, 120A, 120B, 220, 320A, 320B, and 420) according to embodiments ofthe invention generally provide thermal exchange surfaces, withincreased surface area, to heat, cool, and/or regulate the temperatureof an extremity of a mammal. The thermal exchange units can be used toregulate the blood flow in an appendage by a variety of means. Forinstance, applying a temperature to a hand of about 0° C. to 10° C. cancause an increase in the average blood flow due to a phenomenon calledthe “hunting response” which keeps hunters and fisherman from gettingfrostbite while working in the extreme cold with their bare hands.Different individuals respond differently to cold applied to the hands,and in a some well known laboratory tests, application of cold to thehands of a person from the Indian sub-continent improved average bloodflow, but not as much as the same treatment improved the average bloodflow in the typical Eskimo.

In some cases, the perception of warmth is enough to improve blood flow.For instance, a 23° C. (room temperature) water pad feels cool inintimate contact with the leg of a normothermic subject who otherwisefeels warm, and the “COOLNESS” of the pad can measurably reduce bloodflow in the leg. However, if the same person's leg has been exposed to5° C. cold for prolonged periods, this same 23° C. (room temperature)water pad feels warm in comparison, so that it can actually increaseblood flow in the same leg. Therefore the temperature blood flowrelationship is determined by both perceived warmth and appliedtemperature. The application of the heat above the core body temperatureis also able to increase blood flow.

It is noted that one or more thermal exchange units individually or incombination, can be positioned and attached to one or more portions ofthe body element of the invention to provide thermal exchange andregulate the temperature of a mammal's extremity provided inside thedevices as described herein. In one embodiment, one or more thermalexchange units can be pre-assembled inside the devices. In anotherembodiment, one or more thermal exchange units can be assembled into thedevices prior to use.

FIG. 6A is a side view of one example of a device 600, which may be usedincrease blood flow and control the temperature of a lower extremity ofa mammal, such as a foot, according to one embodiment of the invention.The device 600 includes a body element 610 for forming a pressurizedvolume, one or more thermal exchange units 620A, 620B positioned onvarious sides/portions of the extremity 130, the opening 112 forcontaining the extremity 130, and a sealing element 640 attached to theopening 112. An additional sealing element, such as a sealing element642, may be used to adequately seal the extremity 130 within an internalregion 613 of the device 600.

The body element 610 is generally be flat or occupying a minimized spaceor volume such that the device 600 can easily and conveniently befolded, stored, or shipped. The body element 610 is capable of expandingfrom the minimized volume into an expanded space or volume forcontaining a portion of an extremity of a mammal therein. Under apressurized condition, the volume or space of the body element 610 isreduced from the expanded volume into a pressurized volume, such as avolume to conformably enclose the portion of the extremity 130. As aresult, the pressure applied to the extremity 130 enclosed inside theinternal region 613 of the device 600 is distributed evenly and equally.The minimized volume and the expanded volume can be maintained underatmospheric pressure.

The body element 610 may be comprised of the same collapsible and pliantmaterial as the body element 110, such as a transparent orsemi-transparent material that allows viewing of the extremity 130positioned therein. The thickness of the collapsible and pliant materialis not limited as long as it can sustain the pressurized conditions whenthe device 600 is used; for example, a thickness of from about 0.5 milsto about 20 mils, such as about 1.5 mils to about 12 mils, can be usedto pliantly conform to the shape and size of the portion of theextremity 130 contained therein. Accordingly, the materials of the bodyelement 610 and the thermal exchange units 620A, 620B are made of aflexible material, which can be pliant and easily collapsible to conforminto the shape of the extremity 130 and securely surround and enclosethe portion of the extremity 130. The material for the thermal exchangeunits 620A, 620B and the body element 610 are generally comprised ofcollapsible and pliant material similarly discussed above in conjunctionwith thermal exchange units (e.g., reference numerals 120, 120A, 120B)and body element 110. The materials used in the thermal exchange units620A, 620B and/or the body element 610 are generally selected to allowgood contact between the surfaces of the extremity 130 and the thermalexchange units 620A, 620B and/or the body element 610 when asub-atmospheric pressure or a vacuum pressure level is achieved withinthe internal region 613 of the device 600.

The one or more thermal exchange units 620A, 620B, etc., are attached toone or more portions of the body element 610 and adapted to contact aportion of the extremity 130 that is under the pressurized condition,and to increase, reduce, or maintain the temperature of the extremity130 received therein. The thermal exchange unit 620A, 620B can bepermanently or detachably placed inside the device 600 to providethermal exchange for the extremity 130 received therein. In one example,the thermal exchange units discussed in conjunction with FIG. 5A or 5Bcan be adapted to meet the configuration requirements of the thermalexchange units 620A, 620B shown in FIGS. 6A-6C. Alternatively, thethermal exchange unit may include an electric pad, as described indetail in co-pending U.S. provisional patent application Ser. No.60/821,201, filed Aug. 2, 2006, which is incorporated by referenceherein.

The body element 610 may include one or more apertures for attachingvarious fluid ports or pressure ports, such as a pressure port 616, apressure sensing port 618, the fluid supply line 624, and the fluidreturn line 622, among others. Accordingly, one or more thermal exchangesupply lines and one or more thermal exchange return lines can beconnected to one or more thermal sources through the one or moreapertures on the body element 110. As shown in FIG. 6A, one or moretubing's, lines, and ports can be bundled together and connected to amanifold 614 to allow the fluid sources 161, pumps 163, vacuum sensor162 and/or a controller 160 to be easily connected for easytransportation and operation. In one embodiment, the manifold 614, asshown in FIG. 7, incorporates quick-connecting and quick-disconnectingfittings, similar to CPC Colder Products Company in St, Paul, Minn. Inaddition, the manifold 614 may be formed on a portion of the bodyelement 610 for connecting the various fluid ports or pressure ports topass through the one or more apertures of the body element 610 to othervacuum manifold, fluid sources outside of the device 600 through variouskinds of tubing's and/or manifold connectors. The manifold 614 may beconnected to the one or more apertures of the body element 610, the oneor more pressure ports and the one or more thermal exchange units of thedevice 600. The position of the apertures for the fluid ports orpressure ports can be located near any convenient portions of the bodyelement 610 and can be close to the manifold 614 or grouped together forpassing through the body element 610 via a single aperture. FIG. 6Dillustrates another configuration of the device 600 in which themanifold 614 is attached to a desired region of the body element 610 toprovide a central place where connections can be made to the internaland external components in the device 600.

The sealing element 640 is formed on a portion of the opening 112 andadapted to seal the portion of the extremity 130 when placed inside thepressurized volume of the body element 610 so that a pressurizedcondition can be applied to the mammal's extremity. The sealing element640 may be made of the same material as the sealing element 140 (FIG.1A) and can be attached or detachably attached to the opening 112. Inaddition, the sealing element can be used for contacting with the skinof a mammal and capable of producing an airtight seal. The pressurizedvolume defined by the body element 610 and the sealing element 640 ofthe device 600 is created by applying vacuum or negative pressure to thepressure port 616, which can be adapted to be connected to a pump 163(FIG. 6A) to reduce the pressure of the internal region 613. Inaddition, the pressure level inside the chamber or the pressurized,reduced volume enclosed by the body element 610 can be monitored by avacuum sensor 162 placed inside the pressurized volume or space attachedto the pressure sensing port 618. One or more pressure ports may beadapted to be connected to at least one pump 163 on one end and the bodyelement 610 on the other end.

According to an embodiment of the invention, the device 600 can be usedin combination with a mechanical compression device or a pressurizedcompression device. Alternatively, the device can itself be modified toinclude one or more pressure-applying gas plenums in order to applypressurized compression forces, or a positive gas pressure to anextremity of a mammal (e.g., in the internal region 613), while alsoapplying a thermal controlled fluid medium to a fluid exchange unitcontacting the extremity and/or applying vacuum or negative pressure toa portion of the extremity.

FIG. 6B is a perspective view of an exemplary lower extremity devicewhich is not yet folded nor enclosed by the body element 610. FIG. 6C isa perspective view of an exemplary lower extremity device which isfolded, enclosed and sealed according to one or more embodiments of theinvention. The device 600 may include a singular body element 610capable of laying flat, rolled and/or unfolded, as shown in FIG. 6B.Alternatively, the device 600 may include more than one body elements610.

In addition, the device 600 further includes one or more thermalexchange units 620A and 620B capable of containing a thermal-exchangefluid medium therein. The body element 610 and the thermal exchangeunits 620A, 620B can be folded, for example, through the direction ofarrows D, to enclose a portion of the extremity 130 of a mammal. Inoperation the device 600 is folded by securing the positions of thethermal exchange units 620A, 620B and adjusting accordingly to the sizeof the extremity 130. The thermal exchange units 620A, 620B and the bodyelement 610 can be properly folded, secured, and/or adjusted through oneor more enclosing clips 652 located on one or more positions on thethermal exchange units 620A, 620B and the body element 610. The one ormore enclosing clips 652 can be, for example, Velcro type fasteners, asshown in FIGS. 6B and 6C, or another other suitable, clips, fasteners,zippers, snaps, tabs, tongs, adhesives, Velcro fasteners, hydrogelcoated tabs, conventional tapes, buttons, occlusion cuff, hook/loop typesystems, etc. before or after a leg is positioned therein. Next, thebody element 610 can then be positioned over the thermal exchange units620A and 620B to form the opening 112 in which the extremity 130 isdisposed. The size of the opening 112 may be sealed by the sealingelement 640 (FIG. 6A).

Further, a generalized port 625 can be used to bundle up various fluidports and pressure ports together and connected to the controller 160,the fluid source 161, vacuum sensor 162 an/or a pump 163. The one ormore tubing's, lines, and ports can be bundled together and connected tothe manifold 614 for connecting to thermal regulation fluid sources,vacuum pumps, and/or a controller unit (not shown) for easytransportation and easy connection. As shown in FIGS. 6B and 6C, themanifold is convenient located to near the front toe portions of a foot.FIG. 6D illustrates a convenient connection near the heal of a foot.

Referring to FIG. 6C, in one embodiment, the thermal exchange units620A, 620B contain one or more relieved regions 623 that allow formovement of the extremity 130 during the use of the device 600. Theplacement of the relieved regions 623 in the thermal exchange units620A, 620B may be strategically positioned to only allow heat transferto desired regions of the extremity 130. It has been found thatexchanging heat with certain areas of certain extremities can beunpleasurable. For example, it has been found that providing heat to theheal region of a foot can be an unpleasurable experience for somesubjects, and thus, as shown in FIG. 6C, the heal region of the thermalexchange units 620A, 620B has been removed to form the relieved region623 at the heel. In one embodiment, the heat transfer portion of thethermal exchange units 620A, 620B near the heal region is removed toremove or prevent the process from being unpleasant.

FIGS. 6E and 6F illustrate a plan view of an unfolded device 600 similarto the device illustrated in FIG. 6B that can be used to improve theprofusion and regulate the temperature of patients having differentsized extremities 130. As shown in FIGS. 6E and 6F, the design of thedevice 600 can be deigned to allow various sized extremities 130, ashere a foot, to be received and easily positioned within the same sizeddevice 600. By strategic placement use of the enclosing clips 652 (notshown in FIGS. 6E and 6F) the device 600 may be adjusted to fitdifferent sized extremities, such as different sized feet.

In one embodiment, not shown, the device 600 may include one or morebody elements 610 each having an internal region 613 and one or morethermal exchange units disposed therein, such as an first body elementfor forming a first vacuum chamber on the foot portion of a leg and asecond body element for forming a second vacuum chamber on the calfportions up to or near a knee of a leg. Alternatively, one single vacuumchamber may be formed into the device 600 for the whole leg portion of amammal.

FIGS. 12A-12B illustrates an embodiment of the invention in which adevice 1400 can be positioned over a desired portion of skin 1431 of amammal 1430 to increase the blood flow and control the temperature ofthe mammal 1430. FIG. 12A is a cross-sectional side view of the device1400 that has been applied to the skin 1431 of a mammal 1430. FIG. 12Billustrates a plan view of the device 1400 that has been applied to theskin 1431 of the mammal 1430. The device 1400 generally contains bodyelement 1410 and one or more thermal exchange units 1420. The bodyelement 1410 generally contains a sealing element 1411 and compliantelement 1412. In general, the body element 1410 components can be madeof a disposable low cost material, a biocompatible material, a materialthat can be sterilized, and/or a hypo allergic material similar to thematerials discussed above in conjunction with the body element 110. Thecompliant element 1412 is generally formed from a collapsible and pliantmaterial, including but not limited to, urethane, polyurethane,polypropylenes, polystyrenes, high density polyethylene's (HDPE), lowdensity polyethylene's (LDPE), poly(vinyl chloride), rubbers,elastomers, polymeric materials, composite materials, among others. Thecompliant element 1412 can be made of a transparent or semi-transparentmaterial that allows viewing of the skin 1431 region of the mammal 1430.The thickness of the compliant element 1412 is not limited as long as itcan sustain the pressurized conditions when the device 1400 is used. Inone example, a thickness from about 1.5 mils to about 12 mils can beused to pliantly conform to the shape and size of the portion of theskin 1431 contained therein.

The sealing element 1411 is generally used to form a seal to the skin1431 of the mammal 1430 so as to enclose the one or more thermalexchange units 1420 in an internal region 1413. The sealing element 1411is generally designed to form a seal between the body element 1410 andthe skin to allow a pressurized condition to be applied within theformed internal region 1413 by use of the control system 164 and theother supporting equipment discussed above (e.g., reference numerals160-163). The sealing element 1411 can be made of a sticky sealmaterial, such as hydrogel, polyurethane, urethane, among others.Another example is a PS series thermoplastic polyurethane from DeerfieldUrethane, Inc. Disposable sealing materials may be manufactured andpackaged such that they are sterile before use and/or hypoallergenic tomeet health and safety requirements. The sealing element 1411 mayinclude an air permeable portion and/or made of a permeable membranematerial or a breathable material to permit the flow of air.

The one or more thermal exchange units 1420 are generally similar to thedevices discussed above in conjunction with FIGS. 5A-5B. In oneembodiment, as shown in FIG. 12A, the one or more thermal exchange units1420 have an insulating layer 1421 disposed on one or more sides of thedevice to reduce heat loss to environment away from the skin 1431 and/orimprove the heat transfer process to the skin 1431.

Referring to FIG. 12B, during operation the control system 164components are used to create a pressurized condition in the internalregion 1413 by use of the various fluid ports or pressure ports, such asa pressure port 1416, a pressure sensing line 1418, the fluid supplyline 1424, and the fluid return line 1422 that pass through one or moreapertures formed in the body element 1410. In one embodiment, theinternal region 1413 is evacuated by use of a vacuum pump (not shown)that is connected to the pressure port 1416 to create a vacuum conditionin the internal region 1413. The sub-atmospheric pressure created in theinternal region 1413 will cause the atmospheric pressure external to thedevice 1400 to urge the compliant element 1412 against the one or morethermal exchange units 1420 and/or skin 1431 to increase the blood flowand control the temperature of the mammal 1430. In this way the device1400 can be positioned on any open area of the subject, such aspositions on a mammal's back, chest, thigh, or neck to increase theblood flow and control the temperature of the subject.

In another embodiment of the device 1400, as shown in FIG. 12C, thedevice 1400 contains a second region 1414 that is positioned between afirst body element 1410A and a second body element 1410B in which a gasis delivered to achieve a positive pressure therein to cause the secondbody element 1410B to push against the one or more thermal exchangeunits 1420 and skin 1431. The pressure delivered in the second region1414 can be any desirable pressure, such as between about 1 mmHg toabout 80 mmHg above atmospheric pressure. In this way the device 1400can be positioned on any open area of the subject, such as positions ona human's back, chest, thigh, or neck to the blood flow and control thetemperature of the subject by application of pressure to the secondregion 1414 and thermal control of the one or more thermal exchangeunits 1420.

In one embodiment, the devices, such as devices 100-600 and 1400 mayinclude one or more compression pads around one or more portions of theone or more body elements containing an extremity. In one example, thedevice 600 includes an inflatable cuff assembly 680 that is positionedaround one or more portions of the body element 610. Each inflatablecuff assembly 680 may include one or more air pockets (i.e., internalsealed region within the inflatable cuff assembly 680) that areconnected to a fluid tubing 682 and fluid delivery device 681 so thatthe air pockets can be filled with air or various fluids when theextremity 130 is positioned inside the device 600 to cause a compressionforce on the extremity 130. In addition, the pressure within the airpockets in the compression pad can controlled using the air or fluidsdelivered from the fluid delivery device 681 to provide a bellow-likemotion to apply various compression pressures or pressurized forces onportions of the extremity 130 intermittedly, consecutively, or otherwisein a time appropriate manner. The one or more thermal exchange units 620and inflatable cuff assemblies 680 of the device 620 can be positionedin an overlapping configuration or separately on one or more portions ofthe body element of the device. It is believed that applying pneumaticcompression pressure or pressurized force on portions of the extremity130 may increase blood flow within the leg, prevent clotting and bloodpooling in the veins, and prevent deep vein thrombosis. FIG. 6Gillustrates is a side view of one embodiment of the device 600, whichalso contains an inflatable cuff assembly 680 that may be used tocompress a portion of the extremity during one or more phases of thetreatment process. The inflatable cuff assembly 680 may include aninflatable cuff 683 (e.g., conventional inflatable cuff, flexiblebladder), fluid delivery device 681 (e.g., mechanical pump), and a fluidtubing 682 that connects the fluid delivery device 681 and a sealedinternal region of the inflatable cuff 683 to allow a delivered fluid toinflate and deflate the inflatable cuff 683 to a desired pressure at adesired time. The inflatable cuff assembly 680 design can be used inconjunction with the other components discussed herein to transfer heatbetween the extremity and the one or more thermal exchanging devices,and also actively pump blood within the extremity by the use ofsequential compression forces applied to the extremity by the inflatablecuff 683 and the fluid delivery device 681 that are in communicationwith the controller 160.

FIG. 7 illustrates an example of a manifold 714 having one or morefittings that are used to connect the various gas, vacuum or fluid linesto various components internal and external to the device 700 accordingto one or more embodiments of the invention. The manifold 714 can beattached to the one or more body elements and thermal exchange units ofthe device through one or more apertures on the body elements and thethermal exchange units. FIG. 7 is a partial cut-away view thatschematically illustrates a device 700 that contains the variouscomponents discussed above in conjunction with the device 100-600 and1400 and the manifold 714 is generally useful in any of theconfigurations discussed herein in. In one aspect, the manifold 714 isused in place of the manifolds 114, 214, 325, 414, and 625 discussedabove.

The manifold 714 generally contains one or more fluid ports or pressureports, such as a pressure port 716, a pressure sensing line 718, a fluidsupply line 724, and a fluid return line 722, which can be connected tothe manifold body 715 or integrally formed using injection molding, heatstacking, adhesives or other manufacturing methods. Accordingly, quickconnect fittings or connectors can be incorporated to provide aconnection point to interface the thermal exchange units, fluid pads,other heating components, electric pads, vacuum lines, pressure sensinglines, etc. For example, the manifold 714 may include connectors 730,732, 734, 736, such as a quick connect type connector similar to CPCColder Products Company in St, Paul, Minn. In operation, the vacuumspace formed in the device 700 requires an robust and airtight seal sothat the thermal heat transfer fluids and/or air external to the devicedoesn't affect the operation of the process. The manifold 714 can bemade out of injection molded plastic materials for its low cost, or anyother suitable materials. A seal is generally formed between themanifold 714, the various one or more fluid ports or pressure ports(e.g., reference numerals 716, 718), and the body element 710 (e.g.,similar to body elements 110, 210) to allow a desired pressure to bereached in the internal region 713 of the device 700 by use of the pump163. The seal formed between the body element 710 and the variouscomponents of the manifold 714 can be created using conventionaladhesives, mechanical force, or o-rings to name just a few.

As shown in FIG. 7, the manifold 714 may be connected to the inlet ofthe thermal exchange units 720A and 720B, which is similar to thedevices discussed in conjunction with FIG. 5A-5B, using the fluid supplyline 724 through one or more fluid supply fittings 754 and conventionaltubing 753 that is in fluid communication with the connector 732 and thefluid supply line 161A of the fluid source 161. The outlet of thethermal exchange units 720A and 720B is connected to the fluid returnline 722 through one or more fluid supply fittings 752 and conventionaltubing 755 that is in fluid communication with the connector 730 and thereturn fluid line 161B of the fluid source 161.

In one embodiment, the internal region 713 of the device 700 isconnected to the pump 163 which is connected to the pressure port 716that contains a connector 736 contained in the manifold 714, and afitting 756 that is disposed within the internal region 713 of thedevice 700. In one aspect, the internal region 713 of the device 700 mayalso be connected to the vacuum sensor 162 which is connected to thepressure sensing line 718 that contains a connector 734 that isconnected to the manifold 714, and a fitting 758 that is disposed withinthe internal region 713 of the device 700.

In operation, a hand, a forearm, a foot, a leg, an upper extremity, or alower extremity (not shown) is disposed within the opening 712 of thedevice 700 and enclosed within the one or more body elements 710 withone or more thermal exchange units 720A, 720B attached thereon and themanifold 714 attached thereto. Alternatively, the device may need to beassembled by folding, rolling one or more body elements and enclosedwith one or more enclosing clips. In addition, one or more detachablethermal exchange units may be pre-assembled inside the device or may beassembled upon disposing an extremity into the device. Then, a vacuumsealing portion 741 of the seal element 740 is wrapped around theopening of the device to form a tight seal and prevent air from enteringthe space between the extremity and the device.

In one embodiment, a fluid sensing assembly 760 is disposed within thefluid supply line 161A to sense the temperature of the fluid enteringthe one or more thermal exchange units 720A, 720B so that heating orcooling elements contained within fluid source 161 can be controlled bythe controller 160. The fluid sensing assembly 760 generally contains abody 762 and one or more sensors 761 that are in thermal communicationwith the fluid being delivered to the one or more thermal exchange units720A, 720B. The one or more sensors 761 may be a thermistor, RTD,thermocouple, or other similar device that can be used to sense thetemperature of the fluid flowing through the body 762 and the fluidsupply line 161A. It is generally desirable to position the one or moresensors 761 as close to the one or more thermal exchange units 720A,720B as possible, to assure that the environment will not affect thetemperature control of the fluid delivered to the one or more thermalexchange units 720A, 720B.

To control the various aspects of the process of increasing the bloodflow and temperature control of a mammal, the controller 160 is adaptedto control all aspects of the processing sequence. In one embodiment,the controller 160 is adapted to control the fluid source 161, the pump163, and all other required elements of the device 700. The controller160 is generally configured to receive inputs from a user and/or varioussensors (e.g., vacuum sensor 162, fluid sensing assembly 760) in thedevice and appropriately control the components in accordance with thevarious inputs and software instructions retained in the controller'smemory. The controller 160 generally contains memory and a CPU which areutilized by the controller to retain various programs, process theprograms, and execute the programs when necessary. The memory isconnected to the CPU, and may be one or more of a readily availablememory, such as random access memory (RAM), read only memory (ROM),floppy disk, hard disk, or any other form of digital storage, local orremote. Software instructions and data can be coded and stored withinthe memory for instructing the CPU. The support circuits are alsoconnected to the CPU for supporting the processor in a conventionalmanner. The support circuits may include cache, power supplies, clockcircuits, input/output circuitry, subsystems, and the like all wellknown in the art. A program (or computer instructions) readable by thecontroller 160 determines which tasks are performable in the device.Preferably, the program is software readable by the controller 160 andincludes instructions to monitor and control the process based ondefined rules and input data.

FIG. 8 illustrates one embodiment of the control system 864 that isconnected to various parts of a device 800 according to an embodiment ofthe invention. The device 800 and control system 864 is similar to thedevices (e.g., reference numbers 100-700) and control system 164discussed above in conjunction with FIGS. 1-7. The control system 864generally contains a controller module 860 having the controller 160therein that houses all the electronics and mechanical parts which arerequired to regulate the temperature, vacuum pressure level, andcompression pressurized force provided to the pressurized volume of thedevice. In this configuration, the control system 864 typicallyincludes, for example, a pump 163, a vacuum sensor 162, conventionaltubing 824, a fluid source 161, a fluid flow sensor 852, a fluid sensingassembly 760, and a temperature sensor 810. The temperature sensor 810is generally a device that is used to measure the temperature of thepatient while the process of increasing the blood flow and controllingthe temperature of the patient is being performed. Temperature of thepatient can be measured in the ear, mouth, on the skin, or rectallyusing an appropriate conventional temperature sensing device. Thecontrol system 864 may also contain a thermal exchange medium pump, aheater, a cooler, thermocouples, a heating medium pump, aproportional-integral-derivative (PID) controller for process control ofthe vacuum and the temperature, one or more power supplies, displaypanels, actuators, connectors, among others, that are controlled by thecontroller 160. The settings and current readings of the variouselements in the of the control system 864 may be conveniently positionedonto a display panel (e.g., lighted display, CRT) which provides anoperator interface. The controller 160 may contain additionalelectronics for optimal operation of the device 800 of the invention. Inalternative embodiments, the vacuum control and temperature control maybe controlled by two different controllers.

The control system 864 may provide safety features including a deviceshutdown feature that is activated if the device sensors, such as thetemperature and pressure sensors, fail or become disconnected. Thecontrol system 864 may also include an alarm circuit or an alert signalif the temperature of the apparatus is not regulated correctly. A reliefvalve may be provided within the vacuum loop of the device such that thechamber may be vented if the vacuum within the chamber exceeds a certainlevel.

In one embodiment, a temperature probe 862 can be provided to measurethe temperature of a portion of a mammal other than a foot, leg, orother extremity where the device is attached to. In another embodiment,a tympanic membrane can be attached to the ear canal as a temperaturesensor 810 to provide core temperature reading. As such, a referencetemperature for the human, such as a patient, can be obtained. Othersensors may include patient's blood flow and blood pressure and heartrate. These data are important to proper patient health care keeping thepatient at normal temperature range and from various thermal maladies.The temperature of the skin in the device could be measured to indicateif the body portion is in a state of vasoconstriction or vasodilatationor what temperature the skin is compared two device fluid temperatures.Temperature of the skin can be measured by different means and differentdevices like Thermocouples, Thermistor, Heat flux and other measuringdevices. Blood flow rate could also be measured and data sent to thecontroller 160.

As shown in FIG. 8, the device 800 can be connected to the pump 163(e.g., mechanical vacuum pump, pump and vacuum ejector) via a vacuumport 812 and a vacuum sensor return line 822 to provide a vacuumpressure or a negative pressure inside the device 800. It is importantto maintain the vacuum and/or negative pressure levels and correctlysense and read out the vacuum/pressure levels inside the device wherethe extremity is exposed to and send the data to a vacuum transducermounted in the controller 160. The vacuum transducer could also belocated in the manifold 714 (FIG. 7) allowing for a better response andmore accurate control of the vacuum levels. The signal controlling thevacuum pump would come through wires from the vacuum transducer tocontrol circuits in the controller 160. Additional set of data, such aspressure data applied to the extremity by the vacuum, could be measuredthrough a series of pressure sensors placed through the device to recordpressure levels and send data to the controller 160 for evaluation. Thecontroller 160 can then adjust the levels of vacuum and the temperaturewithin the device to produce the highest level of blood flow and toincrease the body's core temperature as needed.

In addition, the device 800 with one or more thermal exchange unitstherein may be connected to the fluid source 161 via a thermal exchangemedium supply line 842 and a thermal exchange medium return line 844.Further, the flow of a thermal exchange medium flown inside the thermalexchange medium supply line 842 can be monitored and regulated by thefluid flow sensor 852 and/or fluid sensing assembly 760. In addition, alow fluid led may be used and displayed on the front panel of thecontroller 160 to warn an operator of fluid level in the reservoir of afluid source. Additional sensor will be added to the fluid reservoir tosend a signal when the fluid level is low and more fluid is needed.Further, there may be controlling signal that allow a conventional fluidpump to operate in a mode of returning fluid back from the fluid padswhen the procedure or a single operation of the device is complete.Additionally, the device may include a temperature sensor for the heatedor cooled fluid circulating through various tubing's and fluid lines. Inaddition, the thermal exchange units of the invention may include one ormore temperature sensors and thermocouples to monitor the temperature ofa mammal's extremity and provide temperature control feedback.

These lines and ports of the invention may be bundled, contained, andstrain-relieved in the same or different protective sheaths connected tothe controller 160. The lines may also be contained in the same ordifferent tubing set with different enclosures for each medium used,such as fluid, vacuum, electric heat, and air lines.

In one embodiment, the thermal exchange units are coupled in a closedloop configuration with the fluid source 161 which provides a thermalexchange medium. For example, the thermal exchange unit may be coupledin a closed liquid loop configuration with a liquid tank housed withinthe controller module 860. In one embodiment, one or more resistiveheating elements and/or thermoelectric devices are used to heat or coolthe thermal exchange medium contained in the liquid tank. The closedloop configuration reduces the maintenance requirements for the operatorbecause it minimizes the loss of thermal exchange medium that typicallyoccurs if the thermal exchange unit is detached from the thermalexchange medium source. Contamination of the thermal exchange mediumsource is also minimized by the closed loop configuration. Contaminationof the thermal exchange medium such as water can also be reduced byadding an antimicrobial agent to the thermal exchange medium source. Indifferent embodiments, the thermal exchange medium may be either aliquid or a gas. In practice, the thermal exchange medium flow rateshould be as high as possible. It was found through testing that theinflow temperature and the outflow temperature through the pad should bewithin about <1.0° C. It has also been found that, in certain cases,blood flow did not increase at all if the pad fluid temperature wasbelow 40° C. A high flow rate allows better temperature consistency,results in less thermal loss, and creates better thermal exchange. In aclosed loop configuration including the thermal exchange unit and thethermal exchange medium source, with a total system volume (e.g., 0.75liters), a flow rate (e.g., 2 liters per minute) transfers as much fluidthrough the thermal exchange unit (e.g., twice than a flow rate of 0.35liters per minute).

In an alternative embodiment, the thermal exchange unit and vacuum linesmay be connected to the controller 160 using actuated fittings such asquick connect fittings with an automatic shut off mechanism. Theautomatic shut off mechanism halts the vacuum application and theheating medium flow as soon as the vacuum lines are disconnected.Actuated fittings may also allow the operator to change thermal exchangeunits. In addition, various quick disconnect connectors may be added tothe controller 160 to allow various disposable parts of the device to bedisconnected after each use.

The embodiments of the apparatus described above provide a method ofincreasing blood flow in one or more extremities of a mammal anddecreasing clots within the veins in order to regulate thermal maladiesand/or prevent deep vein thrombosis (DVT). The method includes providingone or more devices of the invention to the mammal and regulating thetemperature of the one or more extremities of the mammal using thedevices. As a result, one or more Arteriovenous Anastomoses (AVAs) bloodvessels inside an extremity of a mammal are vasodilator, andconstriction of the AVA blood vessels is reduced, thereby increasingblood flow and blood volume in the one or more extremities, decreasingthe vessel wall contact time of the blood flow, and decreasing clots inthe veins due to pooling. Any suitable portions of an extremity,preferably an extremity with vasculature that can be vasodilator by thedevice, may be placed into a device and sealed therein.

Referring to FIG. 2, the process of using the device 200 discussed abovegenerally starts by positioning an extremity 130 in the internal region213 of the device 200. While the process of increasing blood flow andthe temperature of a mammal is discussed in conjunction with the device200, this configuration is not intended to be limiting to the scope ofthe invention since any of the devices discussed herein could be used toperform this process. Once the extremity 130 is enclosed in the device200, negative pressure is applied to a pressure port 116 therebylowering the pressure within the internal region 213 and exposing theextremity 130 to decreased pressure in the range, for example, of about0 to about −20 mmHg, such as from about −10 mmHg to about −14 mmHg.Simultaneously or sequentially, a thermal exchange medium is introducedinto one or more thermal exchange units 220 positioned inside theinternal region 213 of device 200. The flow rate of the pump 163 may beconstant and the flow rate need only be to maintain so that a constantpressure can be achieved in the internal region 213. If there is aslight leak in the system the required flow rate may be greater thanabout 6 liters per minute, and is preferably about 4 liters per minuteor lower. In one aspect, the flow rate of the vacuum pump may be betweenabout 4 liters and about 10 liters per minute, but is preferably lessthan about 6 liters per minute.

In one embodiment, the controller 160 manages the thermal exchangemedium and negative pressure for the duration of the treatment, whichmay be about 30 minutes, for example. The duration may be longer orshorter depending on the size of the extremity treated and thetemperature of the extremity. The process may be repeated one or moretimes as needed. In some cases, the duration of the treatment may becycled “on” for a period of time and then “off” for a time period. Inone example, the duration of the treatment is about 1 minute or longerand then off for a period of about 1 minute or longer, which is repeatedfor 5 cycles or more. The controller is configured to halt the treatmentafter each treatment period. A “stop” button on the control unit may beused to turn off both the thermal exchange medium supply and the vacuum.In one aspect, the controller 160 is designed to monitor the expansionof the lower limb to determine venous refilling so that the refill timecan be adjusted as desired. In general, only small amounts of pressureare needed to be supplied to the extremity to cause movement of bloodwithin the extremity, such as between −3 mmHg and about −20 mmHg. In oneexample, the one or more thermal exchange units 220 are brought intocontact with the extremity by applying a negative pressure of about −3mmHg within the internal region to provide good contact for thermalexchange units, and then the pressure in the internal region isincreased to about −20 mmHg for 30 seconds to increase the pressure onthe extremity and cause the blood to be pumped. The pressure applied tothe extremity can then be cyclically varied between a lower pressure anda higher pressure level for a desired number of times. When the cycledpressure drops to a low pressure (e.g., −3 mmHg) level this provide timefor venous refilling.

Embodiments of the invention may be used to increase blood flow andregulate the temperature of a mammal by increasing the temperature ofthe thermal exchange medium delivered to the thermal exchange devices toa temperature as high as possible without burning the mammal. In ahealthy patient, burning of the cells on the appendage can occur if thecell temperature exceeds about 43 degrees Celsius (° C.), but this mayvary with exposure time and rate of thermal transfer. Therefore, thetemperature of the thermal exchange medium is preferably calibrated suchthat skin temperature is maintained at less than 43 degrees Celsius. Forexample, different people have different tolerance levels for differenttemperature ranges, according to their ages, health conditions, etc. Ingeneral, to heat the extremity it is desirable to control thetemperature of the thermal exchange medium and thus the surface of thethermal exchange units to a temperature is between about 30° C. to about43° C. In one embodiment, the temperature of the thermal exchange mediumand thus the surface of the thermal exchange units is between about 37°C. to about 40° C.

In addition, the device can be used to cool the temperature of apatient. In general, a patient's temperature can be maintained, or, ifit is required by the procedure, the patient's core temperature can belowered by active cooling to about 33° C. In general, to cool theextremity it is desirable to control the temperature of the thermalexchange medium and thus the surface of the thermal exchange units to atemperature is between about 0° C. to about 30° C. In one embodiment,the temperature of the thermal exchange medium and thus the surface ofthe thermal exchange units is between about 0° C. to about 10° C.

Consequently, in order to reduce patient discomfort, the controller maybe configured with different temperature and vacuum settings. In oneembodiment, one treatment setting is “High”, which includes the highesttemperature and negative pressure setting. “Medium” and “Low” settingshave progressively lower settings for temperature and/or pressure.Patients who are being treated for an extended amount of time or who areat high risk for additional complications may be treated on the “Low”setting. The pressure setting may be adjusted to provide positive ornegative pressure in patients. For example, extra care is provided forapplying pressure and thermal regulation to patients who are underanesthesia. In one embodiment, the high temperature is about 42° C., themedium temperature is about 41° C., and the low temperature is 40° C.,while the vacuum level remains at about −10 mmHg for all temperaturesettings.

In a further aspect, the device may use between about 5 watts and about250 watts of power to raise a body core temperature at a rate of betweenabout 4° C./hour and about 12° C./hour. Preferably, the power applied isbetween about 5 watts and about 80 watts, although a power of up toabout 250 watts may be used. In contrast, conventional convectivewarming blankets that heats the whole body may use about 500 watts,which is harder to control and is less efficient.

Table 1 illustrates exemplary suitable applied power (in watts) ascompared to contact surface area. In one embodiment, the surface ofcontact between the thermal exchanging units (e.g., reference numerals120A, 120B, 220, 320A, 320B) and the skin of the extremity is betweenabout 30 in² (e.g., 0.019 m²) and about 410 in² (e.g., 0.264 m²). Inanother embodiment, the surface of contact between the thermalexchanging units and the skin of the extremity is less than about 800in² (e.g., 0.516 m²). In general, it is desirable to maximize thecontact between the thermal exchanging units and the skin of theextremity to improve heat transfer. However, it is through the use ofthe AVAs that are primarily found in the extremities that provide themost efficient and controlled heat transfer between the extremity andthe thermal exchanging units.

TABLE 1 1 2 3 4 5 6 7 8 % Area 1.25% 2.5% 4.86% 3.62% 8.28% 16.56%10.25% 13.48% Area 37.5 75.0 145.8 108.6 248.4 496.8 307.5 404.4 sq.inch Watt/sq. inch 0.32 0.32 0.24 0.32 0.24 0.24 0.16 0.16 Watts 12.024.0 35.0 34.8 59.6 119.2 49.2 64.7 Watts to 6.0 12.0 17.5 17.4 29.859.6 6.2 32.4 Core

The testing as described herein was done in lab using a prototype of thedevice as shown in FIG. 1A. The percentage (%) increase per minute inthe local blood volume of the extremity was measure. Volunteer humansubjects were participated in the study. The “% Area” row illustratesthe percentage of area of the patients body covered by the thermalexchanging units (e.g., reference numeral 120A, 120B in FIG. 1A,reference numeral 220 in FIG. 2) used to perform the process. The “Areasq. inch” row illustrates the actual square inches covered by thethermal exchanging units. The “Watt/sq. inch”, “Watts”, and “Watt toCore” are examples of the power and power densities used in exemplaryversions of the devices discussed herein. The columns labeled “1”-“8”illustrate different thermal exchanging unit and device configurations.

FIG. 9 is a graph demonstrating the results of increased blood flowusing the device 100 according to one embodiment of the invention. Theresults were achieved on a female subject using the device shown in FIG.1A. The baseline readings 910 were taken from zero to about 30 minuteson the time scale, no device was used during base line readings. Thereadings 920 from about 30 minutes to about 60 minutes with the device“on” and set to a vacuum level of about −10 mmHg was maintained in theinternal region 113, and a thermal exchange medium temperature of about42° C. was delivered to the thermal exchange units 120A, 120B. Thereadings 930 from about 60 minutes to about 90 minutes the vacuumsetting with the device was set to about −10 mmHg was maintained in theinternal region 113, and a thermal exchange medium temperature of about42° C. was delivered to the thermal exchange units 120A, 120B. Theresults show an increase in blood flow from a baseline of about 1% perminute to about 3% per minute to maximum readings between about 6% toabout 7% during the test.

FIG. 10 is another graph demonstrating the results of increased bloodflow using the device according to another embodiment of the invention.This is a male subject. The baseline readings 1005 were taken from zeroto about 20 minutes on the time scale. The readings 1006 from about 30minutes to about 110 minutes were with device “on” while a vacuum levelof about −10 mmHg was maintained in the internal region 113, and athermal exchange medium temperature of about 42° C. was delivered to thethermal exchange units 120A, 120B. The results show an increase in bloodflow from a baseline of about 2% to about 4.2% per minute to maximum ofabout 8% per minute to about 10% during the test.

FIG. 11 is another graph demonstrating the results of increased bloodflow using the device according to yet another one embodiment of theinvention. This is a female subject; the device was as shown in FIG. 1A.The base line readings 1005 were taken from zero to about 15 minutes.The device was “on” from about 15 minutes to about 60 minutes while avacuum level of about −10 mmHg was maintained in the internal region113, and a thermal exchange medium temperature of about 42° C. wasdelivered to the thermal exchange units 120A, 120B using the device asshown in FIG. 1A. From about 60 minutes to about 85 minutes the vacuumlevel was set to about −10 mmHg and a thermal exchange mediumtemperature of about 42° C. was delivered to the thermal exchange units120A, 120B. The results show an increase in blood flow from baseline ofabout 2% per minute to about 4.5% per minute to maximum readings ofabout 12% to about 14% during the test.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of preventing and/or reducing a risk ofdeep vein thrombosis (DVT) in an appendage of a mammal, comprising:cyclically varying pressure within an internal region of a flexible bodyof a device, wherein one or more first flexible walls of the flexiblebody at least partially enclose the internal region, and the flexiblebody defines an outermost surface of a portion of the device, and theportion of the device is configured to be disposed over a portion of theappendage of the mammal when the portion of the appendage is disposedwithin the internal region through an opening that is formed withinflexible body, and wherein the method of cyclically varying pressurewithin the internal region comprises: (a) adjusting the pressure withinthe internal region to a first pressure level that is below atmosphericpressure, wherein the adjusted pressure causes the one or more firstflexible walls to collapse against the portion of the appendage that isdisposed within the internal region, and the flexible body is configuredto substantially conform to the shape of the portion of the appendagewhen the first pressure level is achieved within the internal region;and (b) adjusting the pressure within the internal region to a secondpressure level; and (c) repeating (a) and (b) at least one more timebefore removing the appendage from the internal region.
 2. The method ofclaim 1, wherein the second pressure level is below atmosphericpressure.
 3. The method of claim 1, wherein the second pressure level isabove atmospheric pressure.
 4. The method of claim 1, wherein theflexible body further comprises: one or more second flexible walls thatare sealably coupled to at least a portion of the one or more firstflexible walls to form a first enclosed fluid plenum regiontherebetween, and the method further comprises flowing a thermalexchanging fluid at a first temperature through the first enclosed fluidplenum region.
 5. The method of claim 4, wherein the first temperatureis between about 30° C. and about 43° C.
 6. The method of claim 1,wherein the adjusting the pressure within the internal region to thefirst pressure level further comprises adjusting the pressure to a levelof about −20 mmHg and maintaining the first pressure level for a firstperiod of time, and then adjusting the pressure within the internalregion to the second pressure level further comprises adjusting thepressure to a level between −3 mmHg and −20 mmHg and maintaining thesecond pressure level for a second period of time.
 7. The method ofclaim 6, wherein the first temperature is between about 30° C. and about43° C.
 8. A method of preventing and/or reducing a risk of deep veinthrombosis (DVT) in an appendage of a mammal, comprising: cyclicallyvarying pressure within an internal region of a flexible body of adevice, wherein one or more first flexible walls of the flexible body atleast partially enclose the internal region, one or more second flexiblewalls are sealably coupled to at least a portion of the one or morefirst flexible walls to form a first enclosed fluid plenum regiontherebetween, the flexible body defines an outermost surface of aportion of the device, and the portion of the device is configured to bedisposed over a portion of the appendage of the mammal when the portionof the appendage is disposed within the internal region through anopening that is formed within flexible body, and a flexible compressionpad having an internal pocket region that is disposed over at least aportion of the appendage, and wherein cyclically varying a pressurewithin the internal region comprises: (a) flowing a thermal exchangingfluid at a first temperature through the first enclosed fluid plenumregion; (b) adjusting the pressure within the internal region to a firstpressure level that is below atmospheric pressure, wherein the adjustedpressure causes the one or more first flexible walls to collapse againstthe portion of the appendage that is disposed within the internalregion, and the flexible body is configured to substantially conform tothe shape of the portion of the appendage when the first pressure levelis achieved within the internal region; and (c) adjusting the pressurewithin the internal pocket region to a second pressure level; (d)adjusting the pressure within the internal pocket region to a thirdpressure level; and (e) repeating (c) and (d) at least one more timebefore removing the appendage from the internal region.
 9. The method ofclaim 8, wherein the second pressure level is below atmosphericpressure.
 10. The method of claim 8, wherein the second pressure levelis above atmospheric pressure.
 11. The method of claim 8, wherein thefirst temperature is between about 30° C. and about 43° C.
 12. Themethod of claim 8, wherein the adjusting the pressure within theinternal region to the first pressure level further comprises adjustingthe pressure to a level of less than or equal to −20 mmHg andmaintaining the first pressure level for a first period of time.
 13. Themethod of claim 12, wherein the first temperature is between about 30°C. and about 43° C.
 14. A method of preventing and/or reducing a risk ofdeep vein thrombosis (DVT) in a mammal using a device, comprising:positioning at least a portion of an extremity of a mammal in aninternal region of a flexible body, wherein the flexible body comprises:one or more first flexible walls that enclose at least a portion of afirst internal region, wherein at least a portion of the flexible bodydefines an outermost surface of a portion of the device; an openingformed in the flexible body that is configured to receive the portion ofthe extremity and allow the portion of the extremity to be positionedwithin the first internal region; one or more second flexible wallssealably coupled to at least a portion of the one or more first flexiblewalls to form a first enclosed fluid plenum region therebetween; andvarying the pressure within the first internal region between a firstpressure level and a second pressure level using: a first pump fluidlycoupled to the first internal region and that is configured to generatea pressure below atmospheric pressure within the first internal regionto cause the one or more first flexible walls to collapse against theportion of the extremity disposed in the internal region, wherein theflexible body is configured to substantially conform to the shape of theportion of the extremity when the first pressure level is reached withinthe first internal region.
 15. The method of claim 14, furthercomprising: positioning a first compression pad over at least a portionof the extremity, wherein the first compression pad comprises a thirdflexible wall that encloses at least a portion of a second internalregion; and controlling the pressure in the second enclosed plenumregion using: a second pump fluidly coupled to the second enclosedplenum region and configured to create a pressure above atmosphericpressure within the second internal region to cause the third flexiblewall to press against the at least a portion of the extremity.
 16. Themethod of claim 14, wherein the second pressure level is belowatmospheric pressure.
 17. The method of claim 14, further comprisingflowing a thermal exchanging fluid at a first temperature through thefirst enclosed fluid plenum region, wherein the first temperature isbetween about 30° C. and about 43° C.
 18. The method of claim 14,wherein varying the pressure within the internal region to the firstpressure level further comprises adjusting the pressure to a level ofless than or equal to −20 mmHg and maintaining the first pressure levelfor a first period of time.